This program project brings together a dynamic team of experienced HIV investigators who bring individual and collective strengths to design and test novel vaccines to elicit neutralizing antibodies (NAbs). The overall goal is to design novel vaccines based on env genes from HIV-infected subjects who develop broad NAbs in an accelerated fashion. In Project 1 (L Stamatatos), we will identify multiple HIV-1 infected, ART-naive subjects who developed both autologous and broad cross-neutralizing Abs within the first 2-3 years of infection and characterize the epitope-specificities of these NAbs. With Project 3, we will define changes that accrue to the subjects' cloned quasispecies Envs from initial infection through broadening. We hypothesize that specific diversification of the quasispecies drives maturation of broad cross NAbs in vivo, by presenting new epitopes in escape variants, or by focusing the response on more conserved epitopes. In Project 2 (S Kalams), we will characterize the temporal development and maintenance of functional T-helper (Th) responses that allow B cells to respond to the changes in the Env proteins produced by the patient's quasispecies variants in Project 1. We hypothesize that the initial ability to generate NAbs correlates with a relatively intact CD4+ Th response early in infection, ultimately lost with continued viremia. We will adapt a novel technology to sort Env-specific B cells from these subjects and characterize NAbs that neutralize diverse isolates, to refine our choice of Env immunogens. In Project 3 (N Haigwood), we will work with Project 1 to clone env gp160 variants to define the autologous NAbs and the pathways of env escape; vaccines will be based on these natural longitudinal env variants that arise during broadening. Variants will be used singly and in mixtures to program humoral immunity in vaccinated rabbits and macaques. We hypothesize that the responses in vivo will result in broader NAbs than those elicited by other vaccine strategies. The Program is supported by Core A (Stamatatos) to develop protein immunogens, by Core B (L Picker and M Axthelm) to provide expertise in nonhuman primates and T cell analyses in macaques, and Core C (Haigwood) to support the entire Program with administrative support and biostatistics.